Redundant Steering Motor Control via Asynchronous Force Segmentation
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Solution Overview
Problem
The existing steering systems in motor vehicles face challenges in maintaining operational safety and efficiency due to the need for precise synchronization and equal power delivery between two parallel motorization channels, which can lead to inefficiencies, increased costs, and reduced driving comfort, especially in autonomous driving modes.
Innovation Solution
A control method where one channel delivers a significant part of the total assist force, and the second channel adjusts in real time to compensate for any discrepancies, allowing for asynchronous operation and independent power management, reducing the need for synchronization and enhancing fault tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two motorizations are synchronized to deliver identical actuating power, then operational safety is improved, but control complexity and synchronization requirements increase
Solution Approach 1:
The patent divides the total assist force into two independent channels: a first channel delivering a first part of the force and a second channel delivering a second part. Each channel operates independently with its own control loop, eliminating the need for complex synchronization while maintaining redundant safety. The assist force is segmented into F1 and F2 components that can be controlled separately.
Solution Approach 2:
The patent implements feedback control in each channel by measuring the actual assist force delivered (F1_actuel, F2_actuel) and comparing it with the target force. The control system adjusts the control signals based on the difference between actual and target values, ensuring operational safety without requiring complex inter-channel synchronization.
2Reliability
If two motorizations are synchronized to deliver identical actuating power, then operational safety is improved, but losses and vibrations increase
Solution Approach 1:
By segmenting the assist force into two independently controlled channels, the patent allows each motorization to operate at its optimal point without being constrained by synchronization requirements. This reduces energy losses and vibrations that occur when motorizations are forced to operate in unison despite different operational conditions.
Solution Approach 2:
The patent enables dynamic adjustment of each channel's assist force independently based on real-time measurements. The first channel delivers F1 and the second channel delivers F2, with each being dynamically adjusted according to its own feedback loop, allowing the system to adapt to changing conditions without synchronization-induced losses.
3Reliability
If power supply networks are adapted to ensure equal power delivery, then operational equality is improved, but system costs increase
Solution Approach 1:
The patent applies local quality control by independently managing the power delivery of each channel according to its specific conditions. Instead of forcing both channels to deliver equal power from adapted supply networks, the system allows each channel to deliver its required assist force (F1 and F2) independently, with power management tailored to each channel's needs.
4Productivity
If channels are strongly linked to ensure synchronization, then operational performance is improved, but fault propagation increases
Solution Approach 1:
The patent segments the control system into two independent channels with separate control loops. Each channel measures its own actual assist force (F1_actuel, F2_actuel) and adjusts its control signal independently. This segmentation prevents fault propagation while maintaining operational performance through independent fault isolation.
Solution Approach 2:
The patent treats each channel as an independent, replaceable unit. If one channel fails, the other can continue operating independently without being affected by the failure. This approach prioritizes reliability by allowing individual channel failure without compromising the entire system, effectively using a disposable/fail-safe approach for each channel.
Data Source
AI summary
A method for controlling a steering system of a motor vehicle, including two channels arranged in parallel and each including an electric drive delivering an assistive force for assisting in the steering of the vehicle, so as to obtain a sum of the two delivered assistive forces that corresponds to a total requested assistive force requirement, this method being noteworthy in that a first channel delivers a first portion of the total assistive force requirement, and in that the second channel delivers a variable complementary assistive force portion, corresponding to the difference between the estimated or measured first force portion that is actually delivered and the total force requirement.